Method of pickling metal



Oct. 11,, 1938. N. H. SCHERME'R 2,133,231

METHOD OF PICKLING METAL FiledOct. 19', 19sa :1 7 Map H-L/jer Patented Oct. 11, 1938 UNITED STATES PATENT OFFICE mz'rnon or momma METAL Nathan H. Schermer, Detroit, Mich. Application October 19, 1933, Serial No. 106,365 1 Claim. (01. 148-8) This invention relates to the pickling of metals, but has reference more particularly to a novel method of pickling metals in the form of sheets and strip.

A primary object of the invention is to provide a method of pickling metals wherein a more thorough pickling or cleaning is effected than is possible in the usual methods of pickling, and in a fraction of the time and with much lessmaterial and equipment than'is required in pickling by such usual methods. A further object of the invention is to provide a method of the character described which is preferably continuous in character.

steps hereinafter described and particularly pointed out in the claim, the following description setting forth in detail one approved method of carrying out the invention, such disclosed method, however, constituting but one of the various ways in which the principle of the invention may be used.

The figure is a diagrammatic central vertical section.

The method, broadly stated, consistsin flexing or stretching the metal while exposed to the action of the pickling solution. This flexing or stretching can be accomplished by the use of a scale breaker'or roller leveler immersed in the pickling bath, or by means of an electromagnetic vibrator which acts on the metal while it is so immersed.

The metal is preferably drawn or pulled through the pickling bath by the flexing means or auxiliary devices, such as pinch rolls, and is flexed first in one direction and then in the other direction so that both surfaces of the metal are bent or flexed. Since the scale'or oxide. adhering to the metal has considerably less ductility than the metal itself, the flexing causes the scale to crack and break off, at least the flexing is so performed as to accomplish this result. In some cases, the flexing is carried to a point which results in slightly stretching the metal.

As the scale cracks, the pickling solution immediately wets the bared metal and pickling takes place much more rapidly than in the case where the metal is flrst flexed outside the pickling bath and then passed through such bath. In the former case, the heat generated by the flexing seems'to energize the pickling solution and causes the scale to readily break 01!, while in the latter case, the scale rarely breaks oil and the base metal is therefore not readily wetted. In most hot rolled metals, the scale, owing to the presence of pits and other surface defects, is tightly anchored to the metal, and is extremely diflicult-to remove by the usual pickling methods, such removal usually requiring prolonged pickling resulting in considerable loss of metal and overimmersed in the pickling solution, one being flexed while so immersed and the other left intact. The piece which is flexed becomes pickled almost instantaneously where the scale is broken, but several minutes are required before pickling of the other piece begins.

The flexing or stretching apparatus ispreferably made of an acid-resisting metal, which will operate in a sulphuric acid bath for long periods with very little loss in weight. Such apparatus can be installed in existing pickling tanks, and can be so arranged as to be readily removable from the tank, and in a manner similar to that" in which tinning equipment is removed from a tin plating apparatus.

By way of example, there] is shown in the drawn through the tank by suitable pinch rollers, not shown. This passage of the strip S between the upper and lower set of rollers 3, flexes the strip alternately in opposite directions. All of the flexing, it may be noted, is performed while the strip is immersed in the pickling solution.

Other modes of applying the principle of my invention may be employed, instead of the one explained, change being made as regards the method herein-disclosed, provided the step'or steps stated by the following claim or the equivalent of such stated step orsteps be employed. I therefore particularly point out and distinctly claim as my invention:

The method of pickling metal in strip form which comprises drawing said strip through a pickling solution, flexing it in .one direction, then flexing it in a reverse direction from the first direction and then flexing it in the flrst direction and repeatedly-flexing portions of said stripin such manner while it is immersed, said flexing being suflicient in extent to break the scale on said strip and permit wetting oi. the bored base metal by the solution.

NATHAN 11..

' accompanying drawing apparatus which may be through the solution in the manner shown, being 

